Model train systems have been in existence for many years. In the typical system, the model train engine is an electrical engine which receives power from a voltage which is applied to the tracks and picked up by the train motor. A transformer is used to apply the power to the tracks. The transformer controls both the amplitude and polarity of the voltage, thereby controlling the speed and direction of the train. In HO systems, the voltage is typically a DC voltage. In other systems, the voltage may be an AC voltage transformed from the 60 Hz line voltage available in a standard wall socket.
A variety of mechanisms are used to control velocity of model trains. In the traditional approach shown in FIG. 1, application of power to track 2 by transformer 4 is regulated by twisting a control knob 6 approximately 90°, from a zero power position 8 to a full power position 10.
FIG. 2 shows a simplified cut-away view of the internal components of the conventional transformer 4. Specifically, the control knob controls physical connection between a exposed windings 700 on the secondary side of transformer 4 and mechanical wiper 702 at connection point 705. When the knob 6 and wiper 702 are turned clockwise, wiper 702 allows additional winding 700 of the transformer to be connected on the secondary side of the transformer. This in turn increases the voltage and thus the power available to operate the model train.
When wiper 702 is located at zero position 703, no connection is made on the secondary side of the transformer, and thus no voltage is available to operate the locomotive. This comprises the stopped condition.
When wiper 702 is located at full power position 704, the largest number of turns on the secondary winding is the connection point, and thus all available voltage is supplied to model train. This constitutes the fastest velocity the train can travel.
At any position lying between the no connection point and the maximum number of connected windings, a portion of the maximum voltage will be output of the secondary side. The resolution of this control is determined by the number of secondary winding connections. In a typical transformer, the number of secondary winding connections is between about forty and eighty, over an angular range of knob positions of about 90°.
Conventionally, the power applied by transformer 4 to track 2 is increased as knob 6 is turned in the clockwise direction, and decreased as knob 6 is turned in the counter-clockwise direction. As illustrated in FIG. 1 control knob 6 is typically able to be turned approximately 90°, with the complete range of locomotive speed necessarily lying within this rotational arc.
In another type of control system, a coded signal is sent along the track, and addressed to the desired train, conveying a speed and direction. The train itself controls its speed, by converting the AC voltage on the track into the desired DC motor voltage for the train according to the received instructions.
These instructions can convey commands relating to other than train speed, including for example signals instructing the train to activate or deactivate its lights, or to sound its horn. U.S. Pat. Nos. 5,441,223 and 5,749,547 issued to Neil Young et al. show such a system and are incorporated by reference herein for all purposes. Due to this increase in complexity of model railroading layouts and equipment, it is desired to exercise more precise control over the velocity of locomotives.
For example, the above-incorporated control system utilizes a rotating control wheel to achieve higher resolution of train velocity. Such a control wheel allows continuous rotation in either direction with no fixed starting or stopping point. Such a rotating control wheel typically generates approximately fifty signals per revolution. Thus a particular system featuring a total resolution of two hundred speed steps would require four complete revolutions of the control wheel by the user to move from zero to full speed.
This conventional command control approach to regulating train velocity offers the advantage of conferring greater granularity over the control of velocity. This approach, however, requires that more physical effort be exerted by the user to turn the knob multiple times, in order to produce the same speed resulting from less than one twist of the knob of the device shown in FIG. 1.
This enhanced physical effort offers at least two disadvantages. First, the extra time required to rotate the knob an additional distance may delay responsiveness between train speed and the controller. Second, the required physical manipulation of the control knob over greater distances may strain the wrist tendons/ligaments of a user.
Accordingly, there is a need in the art for a model train velocity controller which allows the user to rapidly exercise precise control over a wide range of speeds.